Safety fears lead to nuclear plant closure: Welsh power station first to be shut down because of possible danger

TRAWSFYNYDD in Snowdonia yesterday became the first British nuclear power station to be closed on safety grounds. Nuclear Electric said that the twin reactor plant, which has not operated since February 1991, would not be restarted.

The decision was greeted with dismay in the local community, where the station provides 490 jobs in a rural area with few other major employers. About 250 staff will be retained for the next three years while the nuclear fuel is removed from the reactor. Nuclear Electric hopes that it may be able to relocate some staff and is offering enhanced voluntary severance to others.

The company has already spent between pounds 6m and pounds 7m over the past two years modifying the plant to make it safer, but Nuclear Electric has been unable to satisfy the Nuclear Installations Inspectorate that the reactors were safe enough.

The company estimates that lost electricity production has cost it about pounds 100m since 1991.

The reactors at Trawsfynydd would almost certainly have been closed in 1995 in any case, when they become 30 years old, because they would have failed the 'long-term safety review' demanded by the nuclear inspectorate at this point in a reactor's lifetime. Nuclear Electric decided that Trawsfynydd should close now because it would not generate enough revenue over the next couple of years to pay for safety modifications. The nuclear inspectors were worried that the steel pressure vessel containing the radioactive reactor core and its carbon dioxide coolant gas could become brittle and crack open. Britain's first generation Magnox reactors have no outer containment buildings, unlike the American-style Sizewell B pressurised water reactor under construction in Suffolk.

The inspectors decided that even though the probability of a crack was very low, the consequences of an uncontained release of radioactivity to the environment were so serious that the reactors could not be allowed to restart without further evidence of their safety.

The design of Trawsfynydd is unique in that welded joints in the steel pressure vessel receive very high doses of neutron radiation from the reactor core. Neutron irradiation embrittles the steel - which is already stressed because of the weld - and makes it more likely to crack.

Nuclear Electric has been arguing that by lowering the pressure and increasing the temperature at which the reactors operated, the steel could be kept warm and ductile and, therefore, safe. But the inspectors were unconvinced and demanded more tests - including the irradiation of test specimens in the other reactors. The tests would have taken so long, and pre-occupied so much manpower that the company decided it was no longer worth trying.

John Collier, the chairman of Nuclear Electric, said: 'Personally, I am very sad that we have had to take this decision. The modifications we have needed to make would have meant a reduced output of electricity over a shorter projected operational life. The station would have been hard pressed to earn enough income from the market over the remainder of its life to cover its costs.'

Nuclear Electric pointed out that the design of Trawsfynydd was unique and that the decision sets no precedent for the other Magnox reactors. Berkeley in Gloucestershire and Hunterston A in Ayrshire have already been closed. The six other Magnox stations still working are expected to stop by about 2003.

Danny Carrigan, national energy officer for the Amalgamated Engineering and Electrical Union, said the closure was 'very disappointing'.

He added: 'We have arranged an immediate meeting with the company to discuss the implications. One thing is for sure, the union will not accept compulsory redundancies in any shape or form.'

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